Post-mastectomy radiotherapy benefits subgroups of breast cancer patients with T1–2 tumor and 1–3 axillary lymph node(s) metastasis

BACKGROUND: To determine the role of postmastectomy radiotherapy (PMRT) in breast cancer patients with T1–2 and N1 disease. PATIENTS AND METHODS. A total of 207 postmastectomy women were enrolled. The 5-year Kaplan-Meier estimates of locoregional recurrence rate (LRR), distant recurrence rate (DRR) and overall survival (OS) were analyzed by different tumor characteristics. Multivariate analyses were performed using Cox proportional hazards modeling. RESULTS: With median follow-up 59.5 months, the 5-year LRR, DRR and OS were 9.1%, 20.3% and 84.4%, respectively. On univariate analysis, age < 40 years old (p = 0.003) and Her-2/neu over-expression (p = 0.016) were associated with higher LRR, whereas presence of LVI significantly predicted higher DRR (p = 0.026). Negative estrogen status (p = 0.033), Her-2/neu overexpression (p = 0.001) and LVI (p = 0.01) were significantly correlated with worse OS. PMRT didn’t prove to reduce 5-year LRR (p = 0.107), as well as 5-year OS (p = 0.918). In subgroup analysis, PMRT showed significant benefits of improvement LRR and OS in patients with positive LVI. CONCLUSIONS: For patients with T1–2 and N1 stage breast cancer, PMRT can decrease locoregional recurrence and increase overall survival only in patients with lymphovascular invasion.